Previously, granular and particulate materials, such as grains, flours, resins, pourable and dry cyanide, etc. have been packaged, shipped and stored in large bulk bags which may contain as much as a ton or more of material. Pourable liquids have also been packaged, shipped and stored in large bulk bags, usually of a woven fabric material by disposing therein a complementary bag or liner made of a flexible plastic film, such as polyethylene. Herein, both these bulk bags and liners will be referred to as bags since they have essentially the same construction, configuration and arrangement and differ in only the particular flexible material of which they are made which is usually a woven fabric and a synthetic resin or plastic film respectively. Some of these bulk bags are flexible and when empty can be folded to a generally collapsed condition.
Flexible bulk bags with generally rectangular ends interconnected by generally rectangular side walls are disclosed and claimed in U.S. Pat. Nos. 4,596,040 and 4,790,029. These bags are made of a woven fabric, plastic film or other flexible material with gusseted panels forming a first pair of opposed sidewalls received between a second pair of opposed sidewalls so that when empty they can be readily folded to a generally flat condition. Usually, these bags have a spout at one or both ends for filling and emptying them. When filled with a flowable material, a plurality of these bags can be stacked side-by-side and one on top of another.
Such a flexible bulk bag of a woven fabric with reinforcing strips woven in the fabric and extending along the side edges and through the central portion of the top, bottom and sidewalls of the bag to thereby reinforce them is disclosed and claimed in U.S. Pat. No. 5,104,236.
For some applications, the sidewalls of a flexible bulk bag are strengthened or reinforced by a band of a flexible fabric material disposed outside or inside the bag and bearing on the sidewalls as disclosed and claimed in U.S. Pat. No. 4,781,475.
While these bags are generally satisfactory for a wide variety of applications, when filled, their sidewalls bulge or bow outwardly and the side edges or corners tend to pull inwardly so that collectively in cross section the sidewalls have a generally elliptical or circular configuration. Thus, hen a plurality of these filled bags are stacked side-by-side with a central portion of their adjacent sidewalls abutting one another, there are void spaces or openings between portions of the sidewalls of adjacent bags. These voids or waste spaces reduce the quantity of material that can be stored in a given floor area or a given cubical volume of storage space, and increase the number of bags required to package and store a given quantity of material. This increases packaging, shipping, storage and handling costs.
One commercially available attempt to solve this problem is a bulk bag of a woven fabric with baffles therein of a woven fabric connected adjacent their side edges to the sidewalls of the bag by stitching. The baffles and stitching extend essentially from the bottom to the top of the sidewalls or essentially across their full vertical height. Each baffle has holes cut through it so that the entire bag can be filled with material and when the bag is filled each baffle is generally planar and extends substantially the entire distance between the top and bottom of the bag. These bags are relatively expensive to manufacture and assemble and because the baffles restrain the flow of material these bags are not entirely satisfactory in use and sometimes the baffles do not adequately restrain the bulging or bowing of their associated sidewalls of the bag.
Moreover, for some applications, the flexible bag is placed inside a generally cubical container having rectangular ends and rectangular sidewalls with at least the sidewalls and the bottom end being substantially rigid and inflexible. While filled the flexible bulk bag must be removed from this rigid cubical container. Thus, it is necessary to make the maximum perimeter of the sidewalls of the filled bag small enough so that at most there is only a relatively small surface area in the central portion of each sidewall bearing on the adjacent rigid sidewall of the container. Otherwise, frictional forces between the sidewalls of the bag and the container would inhibit removal of the filled bag from the container. These filled bags in rigid outer containers not only have void or wasted space between each filled bag and its associated container and the attendant increased costs associated therewith but also require careful sizing of the maximum perimeter of each filled bag to insure it can be removed from its rigid container while still minimizing the amount of void or waste space.